1. Field of the Invention
This invention relates to a magneto-optical light modulator which modulates transmission of light. In particular, the invention relates to a magneto-optical shutter device, which is capable of switching transmittance in response to a variation in incident light intensity and which may be incorporated into a light computing system, an image forming system, or an optical image processing system.
2. Description of Related Art
In the field of magneto-optical devices, several magneto-optical components including a magnetic film deposited on a grooved surface of a substrate, and an image display device using the components, have been disclosed by the present inventor in Japanese Laid-Open Patent Publication Nos. 10-213785, No. 11-7626, No. 11-8120, and No. 11-14814. However, a magneto-optical modulator that utilizes a magneto-optical component having a magneto-optical effect and that exhibits a dependence on intensity of incident light has not been disclosed.
In the field of light modulators, optical switches or optical shutters, which are able to operate faster than known electric switching devices, are known. Such light modulators include nonlinear optical materials having large nonlinear effect, such as artificially fabricated semiconductors having a superstructure, or specific organic materials, in order to achieve operation under the reduced intensity of light.
When the nonlinear material is employed in an optical switch having a micro-resonator, transmittance of a light flux can be controlled in response to a variation of intensity of the light flux. This is referred to as a "light-to-light gate component" or "all-light gate component". The light-to-light gate component can operate with a short switching time. For example, a light modulator having a nonlinear material, which has a laminated film-structure in which gallium arsenide (GaAs) semiconductor thin films and aluminum gallium arsenide (AlGaAs) semiconductor thin films are alternatively deposited with a pitch of no more than 10 nm, can operate with a switching time of 0.5 picoseconds.
A variety of devices such as logic devices and memory devices can be fabricated by assembling the light-to-light gate components. For example, a light computing system can be built using such components. Improvements in the switching speeds of the above-mentioned modulators is necessary to achieve a light computing system capable of operating at a high frequency.
Thus, there is a need for a magneto-optical light modulator that utilizes a magneto-optical film to perform high speed switching in response to variations in incident light flux.